Engine and valve cover therefor having integral air gallery

ABSTRACT

An internal combustion engine having a system for supplying secondary combustion air to the engine exhaust ports is provided with air distribution means incorporated within adjoining portions of the engine cylinder heads and their respective valve covers. The covers may include distribution galleries formed as open-bottom longitudinal recesses which register with distribution passages in the cylinder heads. The cylinder head cover gaskets may be formed with orifices registering with the distribution passages to meter air supplied thereto. The air gallery open recesses permit die casting of the valve covers and internal air galleries to their final dimensions.

United States Patent [1 1 Thornburgh ENGINE AND VALVE COVER THEREFOR HAVING INTEGRAL AIR GALLERY 211 Appl. No.: 434,230

[52] U.S. Cl. 60/305, 123/195 C, 123/198 E [51] Int. Cl. F02b 75/10 [58] Field of Search 60/307, 304, 305;

[56] References Cited UNITED STATES PATENTS 8/1970 Grosseau 60/305 4/1973 Cole 60/305 1 Mar. 11, 1975 3,822,763 7/1974 Adams 123/198 E Primary Examiner-Douglas Hart Attorney, Agent, or Firm-Robert J. Outland [57] ABSTRACT An internal combustion engine having a system for supplying secondary combustion air to the engine exhaust ports is provided with air distribution means incorporated within adjoining portions of the engine cylinder heads and their respective valve covers The covers may include distribution galleries formed as open-bottom longitudinal recesses which register with distribution passages in the cylinder heads. The cylinder head cover gaskets may be formed with orifices registering with the distribution passages to meter air supplied thereto. The air gallery open recesses permit die casting of the valve covers and internal air galleries to their final dimensions.

7 Claims, 7 Drawing Figures ENGINE AND VALVE COVER THEREFOR HAVING INTEGRAL AIR GALLERY FIELD OF THE INVENTION This invention relates to internal combustion engines of the type including means for supplying secondary air to the exhaust ports. The invention also relates to secondary air distribution systems for such engines and to engine valve covers incorporating integral air galleries for such distribution systems.

BACKGROUND OF THE INVENTION It is known in the art to provide an internal combustion engine with a secondary air pump and means connecting the pump with the engine exhaust ports to supply secondary combustion air to the ports for burning residual combustibles in the exhaust gases. The connecting means involved in such air distribution systems commonly include externally mounted air manifolds that connect with distribution tubes or passages extend- .ing through the engine cylinder heads or exhaust manifolds to the exhaust ports at locations close to the valves. With such arrangements, the additional air manifolds required add components and clutter to the engine assembly which it is desirable to avoid.

Some arrangements have also been provided wherein secondary air galleries are incorporated within the engine cylinder heads or the exhaust or intake manifolds. However, these constructions generally require increased complexity in the castings with the additional requirement of forming the galleries by drilling or coring and plugging the open ends thereof in assembly. In such arrangements, additional components are added to the engine assembly which complicate its construction and increase its cost.

SUMMARY OF THE INVENTION The present invention provides improved arrangements of internal combustion engines wherein a secondary combustion air distribution system is in part incorporated within adjoining portions of the engine cylinder head or heads and their respective valve cover or covers. The arrangements minimize the number of components needed in an air distribution system by incorporating air distribution passages within existing components. For example, the air galleries are formed within opposing portions of the cylinder heads and their associated valve covers, each gallery consisting of an open sided longitudinal recess or ditch in one of the opposing members with the open side closed by the other of the members. When the gallery recesses are formed in the valve covers, openings in the cover gaskets may be sized to act as metering orifices. Also, the open sided design of galleries in the valve covers permits die casting or otherwise forming the covers to finished dimensions and avoids any need to drill passages or plug any openings made by drilling or coring during manufacture.

In preferred form, each valve cover is formed as a unitary die cast member and includes an integral air distribution gallery in one wall. The air gallery is formed as an open ditch or recess extending upwardly within the wall from the cylinder-head-engaging surface of the valve cover mounting rim. The recess extends longitudinally along the wall so that it registers with distribution tubes or passages provided within the respective engine cylinder head and extending from the cover mounting surface into the engine exhaust ports. A cast connecting passage within each cover connects its recess or gallery with external conduit means which receive air from an engine driven pump in the usual manner.

The connection of the valve cover with the cylinder head may be sealed with a flat gasket which is arranged to straddle the open edge of the cover recess and seal its edges. Openings provided in the gasket register with the engine distribution passages and may be sized to provide controlled orifices for properly metering the air flow to the various exhaust ports.

These and other features and advantages of the invention will be more fully understood from the following description of certain preferred embodiments taken together with accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is an end view of an internal combustion engine having a secondary air system including a distribution system and valve covers having integral air galleries in accordance with the invention;

FIG. 2 is a transverse cross sectional view showing construction details of a cylinder head and valve cover of the engine of FIG. 1 taken in the plane indicated by the line 22 of FIG. 4 was viewed in the direction of the arrows;

FIG. 3 is a cross sectional view similar to FIG. 2 but taken in a different plane indicated by the line 3-3 of FIG. 4 as viewed in the direction of the arrows;

FIG. 4 is a plan view ofone bank of the engine showing the valve cover and partially broken away to disclose certain internal details;

FIG. 5 is a side view as viewed in the direction of the arrows 5-5 of FIG. 4 and showing additional details of the valve cover and air distribution system;

FIG. 6 is a plan view of the cylinder head gasket utilized in the disclosed engine embodiments, and

FIG. 7 is a fragmentary transverse cross sectional view similar to FIG. 2, but showing an alternative embodiment of cylinder head air distribution passages formed according to the invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring to the drawings in detail, numeral 10 generally indicates an internal combustion engine including a cylinder block 12 having two banks l3, 14 of cylinders, not shown, arranged in V" configuration in known manner. Cylinder heads l6, 17 are mounted on the cylinder banks 13, 14, respectively, and in turn mount valve covers 19, 20, respectively to be subsequently described in detail.

Engine 10 includes conventional pistons connected with a crankshaft, not shown, for deriving power from the engine. A drive pulley 22 is mounted on the end of the crankshaft and connects through a V-belt 23 with a driven pulley 24 of an engine mounted air pump 25 for driving the air pump upon operation of the engine.

The air pump 25 connects through a conduit 27 with a check valve 28 which is in turn teed into a distribution conduit 30. Conduit 30 is in turn connected by fittings 32 with connecting passages 34 formed within the valve covers 19, 20 and leading to longitudinal air galleries 35, also formed within the valve covers as will be subsequently described.

FIGS. 2-5 of the drawings more fully disclose the construction of the engine cylinder heads and valve covers, including certain novel features of the air distribution system. Cylinder head 16 includes the usual cast body which is secured to the end of the cylinder bank 13 closing the outer ends of the cylinders therein. A plurality of recesses 37 in the mounting face of the cylinder head comprise, together with the cylinder clearance volumes, combustion chambers having exhaust valve ports38 in the head controlled by exhaust valves 40 and connecting with associated exhaust ports 41 formed within the cylinder head 16. The exhaust ports are in turn connectible to suitable exhaust manifolds, not shown, which may be utilized for further treatment and disposition of the engine exhaust gases.

The exhaust valves 40 extend in conventional manner through an upper portion of the cylinder head whe reo n are mounted the valve springs 42 and rocker arms 44 which form parts of the mechanism utilized for actuating the valves. A valve cover mounting surface 45 is provided on the cylinder head extending peripherally around the upper ends of the valves and rocker arms in conventional fashion on which the valve cover 19 is mounted.

A plurality of tubes 47 extend through openings 48 in the cast body of the cylinder head 16. The tubes 47 define air distribution passages extending from the interior of the exhaust ports 41 to a portion 50 of the valve cover mounting surface 45 that extends longitudinally along the outer edge of the cylinder head so as to provide for supplying air to the ports in the vicinity of the exhaust valve 40.

Valve cover 19 is preferably formed as a die cast member of aluminum or similar material. Its general configuration is conventional, including generally parallel spaced inner and outer side walls 52 and 53, respectively, connected at their ends by end walls 55, 56. The end and side walls merge into an upper connecting wall 57 to form an elongated enclosure open on its bottom side, as shown in the drawings, and surrounding the upper ends of the engine valves and rocker arms. Around their lower edges, the end and side walls are provided with a thickened peripheral rim 59 which includes a shallow relief 60 recessed in the lower surface thereof and receiving a gasket 62. The gasket engages the mounting surface 45 of the cylinder head and seals the joint between it and the rocker cover 19.

The rocker covers are secured to their respective cylinder heads by means of studs 64 which are mounted in the cylinder heads and extend upwardly through bosses 65, 66 provided on the inner and outer side walls, respectively, of the valve covers. Nuts 67 are provided to secure each cover in place on the studs. Openings 68 are also provided in the cover gasket 62 to fit the gasket over the studs 64.

The longitudinal gallery 35 of, for example, rocker cover 19 is formed by a cast-in recess 69 which extends longitudinally for nearly the length of the outer side wall 53 in which it is formed. The recess 69 is open on its bottom side and is bridged and sealed at its edges by the gasket 62. The outer side wall 53 is thickened to receive the recess so that it has the appearance in cross section, as shown in FIG. 2, of a bifurcated wall having inner and outer sections 70 and 71, respectively. The recess 69 extends longitudinally and is straight except for curved portions 73 which extend around the bosses 66 provided for the studs in the outer side wall 53. As may be seen, the form of the recess as well as the side walls, rim and relieved portions are such as to permit die casting of the valve cover without the use of complex coring for any of the portions heretofore described.

To provide for connection of the galleries. with an air supply, the die construction is complicated, however, by the provision in the rocker covers of the connecting passages 34, one of which extends in cover 19 from the recess 69 diagonally upwardly through the upper connecting wall 57, terminating in an internally threaded connection 74. If desired, the passages 34 might be formed by drilling through a wall section so as to avoid complication of the casting die. With the illustrated construction, however, the heavy wall thickness which would result from such a practice makes desirable the use of a special core for forming the passages 34 in the die casting process.

In operation the engine drives the air pump 25 which supplies air through conduit 27, check valve 28, and distribution conduit 30 to the connecting passages 34 of the engine valve covers 19 and 20 and thence to the air galleries 35. From the air galleries, formed in part by recesses 69, the air is passed through openings 76 provided in the valve cover gaskets 45 into the distribution passage tubes 47 and thence to the engine exhaust ports 41 where it is mixed with the engine exhaust gases for subsequent reaction therewith. Preferably, the openings 68 in the gasket 60 which register with distribution tubes 47 are formed smaller than the internal diameter of the tubes and act as control orifices to properly distribute secondary air from the galleries 35 to the various exhaust ports.

FIG. 7 of the drawing shows an engine arrangement similar to that previously described, differing however in the arrangement of the distribution passages within the engine cylinder head. In the alternative embodiment the passages 78 are formed by downwardly drilled portions 79 and upwardly drilled portions 80 which extend downwardly from the cover mounting surface and upwardly adjacent the exhaust valve, meeting at the center to form a dog leg shaped passage through the cast Wall of the cylinder head. In other respects the arrangement in FIG. 7 is similar generally to that previously described.

While the invention has been described by reference to certain preferred embodiments, it is anticipated that numerous changes could be made within the scope of the inventive concepts disclosed. For example, the valve covers might be made of formed sheet metal or other material rather than die cast. Also, the air gallery recesses may be formed in the cylinder head rather than in the adjoining valve cover. In view of these and other possible variations of the inventive concepts disclosed, the invention is intended to be limited only by the language of the following claims.

What is claimed is:

1. An internal combustion engine of the type having a system for supplying secondary air to the exhaust ports for reaction with combustibles in the exhaust gases, said engine comprising a cylinder block having a plurality of cylinders longitudinally aligned in a bank,

a cylinder head closing the outer ends of said cylinders and defining therewith combustion chambers at the ends thereof, exhaust ports in said cylinder head and connecting with said combustion chambers and exhaust valve means carried in said cylinder head and operable to control communication of said combustion chambers with said exhaust ports, said cylinder head having a peripheral valve cover mounting surface and a plurality of secondary air passages in said head extending between said exhaust ports and said valve cover mounting surface for directing secondary air to said ports, and

a cylinder head cover secured on said cover mounting surface to enclose portions of said valve means. said cover having a side wall one edge of which sealingly engages said mounting surface, said side wall having a longitudinal recess formed therein open along said edge, said recess forming a gallery registering with said cylinder head secondary air passages and closed by the sealing engagement of said side wall with said mounting surface, and means in said cover for connecting said recess with a source of secondary air.

2. An internal combustion engine including means defining a plurality of aligned cylinders closed at outer ends thereof by a cylinder head having exhaust ports connecting with said cylinders, valve means controlling exhaust flow through said ports and a valve cover mounted on said cylinder head, said cylinder head and valve cover having adjoining longitudinal walls adjacent said exhaust ports, wherein the improvement com prises a secondary air gallery formed between said adjoining longitudinal walls of said cylinder head and valve cover by a recess extending in one of said walls longitudinally adjacent each of said exhaust ports, said recess being open its full length through an edge of said one wall which sealingly engages a mounting surface of said other wall to close said air gallery, a secondary air pump mounted on the engine, means connecting said air pump with said cylinder head air gallery and a plurality of air supply passages in said cylinder head connecting said air gallery with each of said exhaust ports.

3. An engine according to claim 2 wherein said longitudinal recess is in said valve cover and further including a gasket between said cylinder head and said cover and sealing the joint therebetween said gasket extending across and closing the open side of said cover recess, and a plurality of openings in said gasket and registering with said cylinder head air supply passages, said gasket openings comprising orifices sized to meter the flow of secondary air from said pump to said exhaust ports in desired proportions.

4. The engine of claim 3 wherein said valve cover is formed as a die casting.

5. A valve cover and integral air gallery for an internal combustion engine, said valve cover comprising a cast member having a pair of generally parallel spaced side walls connected at their ends by end walls generally normal to said side walls and a connecting wall merging into said side and end walls and extending therebetween to define an open sided elongated enclosure, said side and end walls being provided at their edges adjacent the open side of said enclosure with a thickened peripheral rim adapted to sealingly engage the valve cover mounting surface of an associated engine, one of the side walls of said cast member being longitudinally bifurcated to form a longitudinal recess extending a major portion of the length of said one side and open its entire length along its edge within the rim portion of said one side wall, and passage means in said cast member through one of said walls and connecting with said recess to provide means for connecting said recess with an external source of air.

6. A valve cover as defined in claim 5 and wherein said cast member is formed as a die casting without machining except for said air source connecting means.

7. The valve cover of claim 5 in combination with a gasket wherein the thickened rim of said valve cover includes a shallow relief in the surface thereof and spanning the open side of said recess, said gasket comprising a flat member shaped to fit within and substantially fill said relief, said gasket including a plurality of spaced openings registering with said recess and comprising control orifices for air flow from said recess to the air supply passages of an associated engine. 

1. An internal combustion engine of the type having a system for supplying secondary air to the exhaust ports for reaction with combustibles in the exhaust gases, said engine comprising a cylinder block having a plurality of cylinders longitudinally aligned in a bank, a cylinder head closing the outer ends of said cylinders and defining therewith combustion chambers at the ends thereof, exhaust ports in said cylinder head and connecting with said combustion chambers and exhaust valve means carried in said cylinder head and operable to control communication of said combustion chambers with said exhaust ports, said cylinder head having a peripheral valve cover mounting surface and a plurality of secondary air passages in said head extending between said exhaust ports and said valve cover mounting surface for directing secondary air to said ports, and a cylinder head cover secured on said cover mounting surface to enclose portions of said valve means, said cover having a side wall one edge of which sealingly engages said mounting surface, said side wall having a longitudinal recess formed therein open along said edge, said recess forming a gallery registering with said cylinder head secondary air passages and closed by the sealing engagement of said side wall with said mounting surface, and means in said cover for connecting said recess with a source of secondary air.
 1. An internal combustion engine of the type having a system for supplying secondary air to the exhaust ports for reaction with combustibles in the exhaust gases, said engine comprising a cylinder block having a plurality of cylinders longitudinally aligned in a bank, a cylinder head closing the outer ends of said cylinders and defining therewith combustion chambers at the ends thereof, exhaust ports in said cylinder head and connecting with said combustion chambers and exhaust valve means carried in said cylinder head and operable to control communication of said combustion chambers with said exhaust ports, said cylinder head having a peripheral valve cover mounting surface and a plurality of secondary air passages in said head extending between said exhaust ports and said valve cover mounting surface for directing secondary air to said ports, and a cylinder head cover secured on said cover mounting surface to enclose portions of said valve means, said cover having a side wall one edge of which sealingly engages said mounting surface, said side wall having a longitudinal recess formed therein open along said edge, said recess forming a gallery registering with said cylinder head secondary air passages and closed by the sealing engagement of said side wall with said mounting surface, and means in said cover for connecting said recess with a source of secondary air.
 2. An internal combustion engine including means defining a plurality of aligned cylinders closed at outer ends thereof by a cylinder head having exhaust ports connecting with said cylinders, valve means controlling exhaust flow through said ports and a valve cover mounted on said cylinder head, said cylinder head and valve cover having adjoining longitudinal walls adjacent said exhaust ports, wherein the improvement comprises a secondary air gallery formed between said adjoining longitudinal walls of said cylinder head and valve cover by a recess extending in one of said walls longitudinally adjacent each of said exhaust ports, said recess Being open its full length through an edge of said one wall which sealingly engages a mounting surface of said other wall to close said air gallery, a secondary air pump mounted on the engine, means connecting said air pump with said cylinder head air gallery and a plurality of air supply passages in said cylinder head connecting said air gallery with each of said exhaust ports.
 3. An engine according to claim 2 wherein said longitudinal recess is in said valve cover and further including a gasket between said cylinder head and said cover and sealing the joint therebetween said gasket extending across and closing the open side of said cover recess, and a plurality of openings in said gasket and registering with said cylinder head air supply passages, said gasket openings comprising orifices sized to meter the flow of secondary air from said pump to said exhaust ports in desired proportions.
 4. The engine of claim 3 wherein said valve cover is formed as a die casting.
 5. A valve cover and integral air gallery for an internal combustion engine, said valve cover comprising a cast member having a pair of generally parallel spaced side walls connected at their ends by end walls generally normal to said side walls and a connecting wall merging into said side and end walls and extending therebetween to define an open sided elongated enclosure, said side and end walls being provided at their edges adjacent the open side of said enclosure with a thickened peripheral rim adapted to sealingly engage the valve cover mounting surface of an associated engine, one of the side walls of said cast member being longitudinally bifurcated to form a longitudinal recess extending a major portion of the length of said one side and open its entire length along its edge within the rim portion of said one side wall, and passage means in said cast member through one of said walls and connecting with said recess to provide means for connecting said recess with an external source of air.
 6. A valve cover as defined in claim 5 and wherein said cast member is formed as a die casting without machining except for said air source connecting means. 